3 vs. 4

ViperDriver · #1 07-08-2007, 11:10 PM

Whats up? I am a debating on starting either a 3 or a 4. Looking for all the pro/con input I can get. I really enjoy aerobatics and am wondering how much performance I will sacrifice going with the four and the extra seat. Thanks to all you experts in advance!

Red Voodoo · #2 07-09-2007, 05:55 AM

Assuming you'll have continued access to the 7A you're co-building, you've got any passenger-carrying needs you may have covered. I doubt an RV-4 gives up much in the way of performance to a similarly-powered -3, but the -3 is still the purest sport plane out of all of Van's designs. Build it light and straight, put an O-320 under the cowl, and have a ball!
(I may be a bit biased here... I've got some RV-3 bits that I hope are going to lead to a second project after the RV-9A is flying!)

the_other_dougreeves · #3 07-09-2007, 06:52 AM

If the -4 came in a pre-matched hole version, even without a QB, I'd start it tomorrow. I've flown a -4 (long ago) and that combined with my experiences with the -7 and -8 suggest that I'd love that airplane.

The -3 may fly slightly better than the -4. However, several of us were chatting about this very issue over a $50 burger and one description that came up was that the -4 was a -3 with a large luggage compartment, and made for a better traveling machine. The -3 and -4 are rated for (IFIRC) 30 lb luggage - not much.

I agree - The -4 isn't for long trips with two people because of useful load and small back seat. However, as a personal machine and for occasional 2-place flying, the -4 is great. The visibility is fantastic.

ViperDriver · #4 07-09-2007, 07:23 AM

Thanks for the input. I can see the potential of going with the four. Not to redirect this too far, but is there a possibility to put an additional fuel tank in the extra seat of the four?

Also what are the options for putting the most power under the hood? Can anyone give me an idea of whats been done. With the savings, I would really like to put inverts on this thing and a constant speed - Thanks. I apologize for my ignorance.

DeltaRomeo · #5 07-09-2007, 07:33 AM

Quote:

Originally Posted by the_other_dougreeves

snip....The -3 may fly slightly better than the -4.

TODR!

Talked with K.Krueger about the 3v4 thing a few times in the past and he states that the -4 will outturn the -3 (different airfoil) all other things equal (same engine/prop).

Plus you can carry baggage if you need to (cargo varient)

.

Of course, either would be fine to have ;^)

b,
d

ViperDriver · #6 07-09-2007, 07:37 AM

Awesome thanks

L'Avion · #7 07-09-2007, 08:01 AM

Someplace in these forums there are some views as to slider vs. tip-over canopy. Research these for personal preference.

Barney

n2prise · #8 07-09-2007, 09:52 AM

The most WORLD-famous RV-4 is well documented on Van's web site at http://www.vansaircraft.com/public/jj-persn.htm. Jon Johanson has flown his RV-4 around the world three times, and once across the South Pole in an abortive attempt to fly non-stop from New Zealand to South America over the South Pole. If you want a globe-trotting RV, the story about this one will tell you how to do it. He and his plane hold several world records.

Jerry K. Thorne
East Ridge, TN
RV-9A - - N2PZ
"Enterprise"
Hobbs = 234.7 hours after two years of flying.

patterson · #9 07-09-2007, 11:55 AM

Mayor,

I built a -4 that was certified in August last year. I used the long-range tanks that fit into the leading edge lightening holes. Gives me 8 gallons, or about an extra hour of range. They're made by Hotel Whiskey.

If I could do it over, I would have simply used RV-6 tanks and saved at least 10 pounds of weight and the complexity of 4 tanks to manage. I also cut down an -8 slider canopy and completely did away with the center roll-over bar (far better visability for you passenger). It's a great airplane, and if your wife/girlfriend is under say 140 pounds, it's just fine for cross country.

That said, I'm looking at building the F4 Rocket-Lite. Mark Friedrick's F1 Rocket with a 4 cylinder IO-360 instead of a 6 cylinder up front. Seems to me this is the ultimate upgrade from my airplane, which I love. The F-4 is faster, still a 4 cylinder so not much heavier, and has more room for both pilot and passenger. On paper that concept is hard to beat in my opinion. We'll see when the first few actually fly.

YMMV,
Ron
RV-4 / N8ZD

frankh · #10 07-09-2007, 12:14 PM

I have seen a lot of 4's with IO360's in them and CS props.

And some of those are tweaked well beyond 180Hp.

Sounds like fun to me!

Frank 7a